Neptune has 14 known moons. Triton is far and away the largest of Neptune’s satellites. The space probe Voyager 2 revealed fascinating details about Triton. Part of its surface resembles the rind of a cantaloupe. Ice volcanoes spout what is probably a mixture of liquid nitrogen, methane and dust, which instantly freezes and then snows back down to the surface.
| 1. Naiad | 2. Thalassa | 3. Despina | 4. Galatea | 5. Larissa | 6. Hippocamp |
| 7. Proteus | 8. Triton | 9. Nereid | 10. Halimede | 11. Sao | 12. Laomedeia |
| 13. Neso | 14. Psamethe |
| Name | Naiad |
|---|---|
| Discovery date | 1989 (Voyager 2) |
| Semi-major axis | 48 200 km |
| Diameter | 58 km |
| Orbital period (Length of a year) |
0.294 Earth days |
| Name | Thalassa |
|---|---|
| Discovery date | 1989 (R. Terrile, Voyager 2) |
| Semi-major axis | 50 100 km |
| Diameter | 80 km |
| Orbital period (Length of a year) |
0.311 Earth days |
| Name | Despina |
|---|---|
| Discovery date | 1989 (S. Synnott, Voyager 2) |
| Semi-major axis | 52 500 km |
| Diameter | 148 km |
| Orbital period (Length of a year) |
0.335 Earth days |
| Name | Galatea |
|---|---|
| Discovery date | 1989 (S. Synnott, Voyager 2) |
| Semi-major axis | 62 000 km |
| Diameter | 158 km |
| Orbital period (Length of a year) |
0.429 Earth days |
| Name | Larissa |
|---|---|
| Discovery date | 1982 (H. Reitsema, W. Hubbard, L. Lebofsky, D. Tholen) |
| Semi-major axis | 73 500 km |
| Diameter | 192 km |
| Orbital period (Length of a year) |
0.555 Earth days |
| Name | Hippocamp |
|---|---|
| Discovery date | 2013 (Mark Showalter) |
| Semi-major axis | 105 283 km |
| Diameter | ~ 16 – 20 km |
| Orbital period (Length of a year) |
0.9362 Earth days |
| Name | Proteus |
|---|---|
| Discovery date | 1989 (S. Synnott, Voyager 2) |
| Semi-major axis | 117 600 km |
| Diameter | 416 km |
| Orbital period (Length of a year) |
1.122 Earth days |
| Name | Triton |
|---|---|
| Discovery date | 1846 (W. Lassell) |
| Semi-major axis | 354 800 km |
| Diameter | 2706 km |
| Orbital period (Length of a year) |
5.877 Earth days |
| Name | Nereid |
|---|---|
| Discovery date | 1949 (G. Kuiper) |
| Semi-major axis | 5 513 400 km |
| Diameter | 340 km |
| Orbital period (Length of a year) |
360.14 Earth days |
| Name | Halimede |
|---|---|
| Discovery date | 2002 (M. Holman, J. J. Kavelaars, T. Grav, W. Fraser, D. Milisavljevic) |
| Semi-major axis | 15 686 000 km |
| Diameter | 48 km |
| Orbital period (Length of a year) |
1874.83 Earth days |
| Name | Sao |
|---|---|
| Discovery date | 2002 (M. Holman, J. J. Kavelaars, T. Grav, W. Fraser, D. Milisavljevic) |
| Semi-major axis | 22 452 000 km |
| Diameter | 38 km |
| Orbital period (Length of a year) |
2918.94 Earth days |
| Name | Laomedeia |
|---|---|
| Discovery date | 2002 (M. Holman, J. J. Kavelaars, T. Grav, W. Fraser, D. Milisavljevic) |
| Semi-major axis | 22 580 000 km |
| Diameter | 38 km |
| Orbital period (Length of a year) |
2982.27 Earth days |
| Name | Neso |
|---|---|
| Discovery date | 2002 (M. Holman et al., B. Gladman et al.) |
| Semi-major axis | 46 570 000 km |
| Diameter | 60 km |
| Orbital period (Length of a year) |
8863.08 Earth days |
| Name | Psamathe |
|---|---|
| Discovery date | 2003 (D. C. Jewitt, J. Kleyna, S. S. Sheppard) |
| Semi-major axis | 46 738 000 km |
| Diameter | 38 km |
| Orbital period (Length of a year) |
9115.9 Earth days |
